The present invention relates generally to brushes and the art of brush making, and more particularly, to brushes having monofilament bristles and methods of assembling monofilament bristle sub-assemblies to brush bodies.
Brush making involves the attachment of bristles to a brush body. In one type of brush, known as the "solid block/staple set," a solid block acting as the brush body is drilled, molded, or otherwise worked to form an array of holes. Individual tufts are placed in individual holes and secured to the block by wire staples, plugs or other anchoring means. Hand drawn brushes are similar except that the tufts are secured by drawing them through the holes with an elongated strand.
Another type of brush employs a "ferrule and monofilaments" technique for attaching the bristles to the brush body. A cluster of monofilaments and cavity creating spacers are inserted into a ferrule and set with a binding resin. Ferrule brushes, such as the paint brush, are used to primarily apply liquids, and in particular, viscous solutions.
In metal strip brushes, fibers are held in a "U" shaped channel of a metal strip by an anchoring wire, string, or monofilament. The channel is then crimped closed to mechanically clamp the proximal end portions of the monofilaments and anchor wire within the strip. Once formed, the brush-strips can be attached to brush bodies or otherwise shaped for specific applications.
Fused brushes are those in which polymeric tufts are fused directly to a brush body that is preferably made of the same material. One variation of fused brushes employs ultrasonic welding to secure polymeric fibers directly to a base.
With respect to the toothbrush, it is now commonplace to employ nylon monofilaments that are grouped together to form "bristle tufts." Each bristle tuft is typically arranged in a circular cluster, and a complete bristle head includes a matrix of bristle tufts arranged in rows or other patterns. The folded proximal bases of the bristle tufts are typically embedded and held in place by an anchor wire that extends across the field of the tufts and into the polymeric material that forms the head portion of the toothbrush body, while the distal ends extend upwardly therefrom, often terminating in a common plane. A more recent tufting method employs the process of cutting the tuft of monofilaments to the desired length, heat fusing the proximal ends and embedding the fused proximal ends into the polymeric material of the toothbrush head.
More recent innovations in the toothbrush art have included bristle tufts cut to provide differing lengths to provide an array of shorter and longer tufts to achieve a desired action on the user's teeth. In some tufts the monofilaments are of differing length. While these improvements can result in better functional aspects of the toothbrush, few innovations have been made over the years in techniques for manufacturing the toothbrush head; this is particularly evident in the manner in which bristles are assembled with the brush body.
In all types of known brushes, the assembly process can represent a substantial portion of the cost of manufacture since individual bristle filaments have to be held in a desired grouping and then bound to the brush body in a manner that ensures that the bristle filaments do not become detached during use. Also, recycling becomes more problematic for brushes which employ metal staples or other combinations of different classes of materials (plastics and metals, for example) in one structure.
A continuing need exists for improved brush designs and methods of manufacturing brushes which are efficient and cost effective.